Describe the bug

Assimp will reorder bone output upon FBX export. While for most use cases this is fine (the bone order itself is not important for rendering a single mesh), but some downstream tools that take multiple meshes except their bones to be in the same order.

To Reproduce
Steps to reproduce the behavior:

1. Take any FBX model
2. Import with Assimp
3. Export same model with Assimp
4. Examine ordering of bones in editor such as Unity

Expected behavior
The bone order between the original and exported should be the same.

Platform (please complete the following information):

• Any
• Latest Version (5.24 I believe)

Additional context
This leads to an error when using LOD with Unity.

Proposed Fix

Inside of FBXExporter.cpp, line 1870 uses a set, along with a comparator. Remove this comparator, and convert the set to a vector, and that should be sufficient to preserve the input order.